Inhibition of SULT1E1-catalyzed sulfation of 7.0 nM estradiol by PCB metabolites. (a) Inhibition of SULT1E1 by 4’-OH PCB 3, 4-OH-PCB 8, 4-OH-PCB 11, 4’-OH-PCB 25 and 4-OH-PCB 52. Control rates for sulfation of estradiol were 37.1, 27.9, 56.0, 71.4, and 62.8 (nmol/min/mg), respectively. (b) Inhibition of SULT1E1 by 4’-PCB 3-sulfate, 4-PCB 8-sulfate, 4-PCB 11-sulfate, 4’-PCB 25-sulfate and 4-PCB 52-sulfate. Control rates for sulfation of estradiol were 58.1, 57.3, 67.2, 75.8, and 20.2 (nmol/min/mg), respectively.